Mkay, first off I think we have fin rot, or either a case of tail biting.
I am going for the tail biting, because I see no whitish rotting edges you know?
There is a possibility SOMHOW the petstore person managed to close his tail in the lid, bc I found a little piece of tail right there at the lid.
So here is what he is displaying.
Lethargy, and leaning against the wall, only coming up to breathe, and it looks like he has a hard time getting up.
He swan kind of erratically for a second after getting air, then stopped and swam back to his spot on the wall.
I haven't fed him yet, since I just got him home, and he is going in the 1 gallon hospital tank with a little plant I will probably throw away afterwards due to contamination.